Numerous hot water recirculation systems are known to exist for delivering hot water to a fixture within a building. The water is recirculated in order to make hot water instantly available at the fixture when the fixture is turned on. Also, hot water is recirculated in order to conserve water usage because unrecirculated water is typically delivered down a drain while an operator of a fixture waits for hot water to reach the fixture.
U.S. Pat. No. 4,201,518 discloses one system for recirculating hot water. Manually operated push button switches are wired into positions adjacent to hot water fixtures, or taps, within a house. The push buttons operate a time delay circuit that turns on a recirculation pump for a set time interval to circulate hot water through the system. However, electrical wiring must be run from each hot water tap in the system to a central control circuit for a recirculation pump. Since hot water taps are distributed throughout a building or home, this can entail a significant amount of wiring. Furthermore, dedicated push button switches need to be wired into locations adjacent each hot water tap. This entails further expense and complexity in installing the system. Furthermore, the use of dedicated push button switches requires that a user manually activate the push button switch in order to initiate hot water recirculation for the respective hot water tap, which requires that a user remember to turn on the switch.
U.S. Pat. No. 5,205,318 discloses another hot water recirculation system. This system uses a cold water line, or pipe, in combination with a hot water line to recirculate hot water. The system is placed near a hot water fixture. The system pulls water from the hot water line and places it into the cold water line until water in the hot water line reaches a set temperature. However, this makes water in the cold water line warm or hot. Additionally, temperature in the cold water line now varies greatly, and this may require that a user needs to aggressively and continuously adjust the fixture in order to realize a desired water temperature at the fixture, as temperature in the cold water line varies. Furthermore, cold water will be wasted at the fixture in order to obtain cold water at the fixture, and hot water that enters the cold water line can end up at other cold water fixtures. Even furthermore, power needs to be installed adjacent to the system, or unit, which is near the fixture. The system is also prone to failure due to accumulation of hard water deposits that can cause the system to stick into an open position, thereby wasting hot water and sending hot water to all the cold water outlets throughout the system.